1. Field of the Invention
Present invention is related to an exposure apparatus for a ball shaped substrate for manufacturing semiconductor devices. More specifically, the present invention is related to a new apparatus which irradiates slight to continuously supplied substrates, each having a ball shape.
At the same time, the present invention is related to a holder for the ball shaped substrate. More specifically, this holder holds and participates in minute positioning of the small ball shaped substrate.
2. Description of Related Art
Generally, semiconductor devices are formed on a flat substrate like a silicon wafer, however recently, the use of a ball shaped semiconductor as a substrate has been suggested.
A ball shaped semiconductor is made to solidify under stress-free conditions. As a result, a ball shaped semiconductor has a substantially complete ball shape. However, the ball shaped semiconductor has the same composition as general semiconductor wafer. Accordingly, a ball shaped semiconductor can be used as a substrate of semiconductor devices.
Compared with an ordinarily flat substrate having the same surface area, the ball shaped substrate has smaller mass according to the geometric character of the ball shape and this character becomes advantageous in proportion to size. Accordingly, the substrate material can be minimized because of use of the ball shaped substrate.
Because the ball shaped substrate is initially a chip shape, no dividing process is necessary. At the same time, the ball shaped substrate can be completely covered with a pasivation film for the same reason and be implemented with raise of wages chip condition without any package. Then, dividing process and packaging process can be omitted.
Furthermore, because of use of the ball shaped substrate, packaging density is improved and a three dimensional arrangement can be formed. By such reasons, the ball shaped substrate is expected to be an important material in the field of semiconductor devices.
Generally, a semiconductor device is formed on the surface of a semiconductor wafer that is a slice of a single crystal semiconductor material. Ordinarily, many semiconductor devices are prepared on one semiconductor wafer and the wafer is cut and divided to many chips.
The so-called photolithography technique is utilized generally in the manufacturing process of a semiconductor device. In this technique, resist material is put on a wafer, and the resist material is exposed by light through a mask. Then, the resist material is changed by the light according to a pattern of the mask and becomes a so-called resist mask. Such a resist mask is utilized for depositing and etching to form devices.
The process of manufacturing of current semiconductor devices, a so-called stepper is used. A steeper comprises an optical apparatus which moves horizontally and exposes a surface of one substrate wafer many times. On the contrary, the ball shaped substrate is irradiated only once. Therefor, a stepper cannot be used as an exposure apparatus for a ball shaped substrate. In addition, a ball shaped substrate must be precisely located while exposed. However, there is no apparatus that handles a ball shaped substrate.
The term "substrate" means "ball shaped substrate" in following description.